How to turn head and upper body toward a target? (MoBu)

Rigging
1

Using Motionbuilder, I’d like a character to turn towards a null object.
I was able to make his head turn using the aim constraint, but I also need his
upper body to turn and bend for some degree.

I tried the aim constraint on the hips effector but that didn’t work out: the hips
were following the target alright but the upper body (shoulders, head) didn’t
move (like they were locked in place). A similar thing happened when I was
constraining FK nodes.

2

A toned down position constraint on the chest effector makes the upper body
converge on the target while another aim constraint on the hips effector makes
the pose more natural. Works quite well.

I just had to make sure that I have the character facing Z+ and not X+ as I
wanted, otherwise the aim constraint on the hip behaves weirdly. (X+ is the
“forward” in Unreal.)